More than 50,000 Australians who served in the Vietnam War will be honoured today on Vietnam Veterans Day, which also marks the 47th anniversary of the Battle of Long Tan.

The battle was one of the bloodiest of the Vietnam War, and saw eighteen Australians killed and two dozen wounded during fire fight with the Viet Cong.

On August 18, 1966, Patricia Amphlett - or Little Pattie as she is better known - was on stage with Col Joye and the Joy Boys performing for the Australian troops just before the battle broke out.

A teenage girl at the time, Little Pattie stood before a cheering open-air audience when the crowd began to scatter.

"It was at the beginning, I think, of show three, or thereabouts, that I could see officers leaving," she said.

"And I thought, 'Wow, I think this is pretty serious now,' and close to 4 o'clock we were given the sign - the index finger across someone's throat, which means, 'Get off!'

"So we finished the song and we got off stage.

"But at the end of that song a lot of action took place within the audience; the word spread that something bad was going on and, indeed, that was the beginning of the Battle of Long Tan."

She says the band's evacuation from the stage was swift.

"I can remember being thrown into a jeep. There was not a word of conversation during that short ride and nor was there any conversation once we were in the choppers," she said.

"I remember sitting right near the edge next to the soldier, I was looking down and I could see thousands and thousands of orange lights, which were the tracers, and that was the battle in the jungle."

One of the Australian soldiers fighting for his life in that darkness was 6-RAR's Private Alan Parr from Tamworth, a member of 12 Platoon D-Company.

"I was going across to see the Col Joye and Little Pattie concert," he said.

"We'd only just got over there and we got called back so, yeah, so I never got to see the concert.

"I mean we didn't expect anything to happen because we'd been there quite a few times before and nothing had happened but it just gradually built up into quite a large battle.

"You don't get a sense of how many people were there - we never knew till quite a few years later, and that's probably the most Viet Cong I'd ever seen in Vietnam in my 12 months."

Every year on the anniversary Mr Parr's mind travels back.

"You always think about the boys who were wounded or killed in Vietnam on the 18th, but this year I'll just stay in Tamworth and I'll meet with the vets up at the memorial," he said.

"It's a funny day for me - like, I think it's just the memories."

The encounter exacted a terrible toll on both sides: 18 Australians were killed and two dozen wounded. A sweep of the battlefield the following day uncovered nearly 250 Viet Cong bodies.

Surviving Australian soldiers were ordered to bury their enemy combatants.

National president of the Vietnam Veterans Association of Australia, Ken Foster, says 47 years on, the Battle of Long Tan remains a powerful episode in the collective psyche of those who served in the Vietnam War and those who survived it.

"Most of the soldiers that went into Vietnam, but particularly the Taskforce Area, after that battle would use that as an inspiration for their time there," he said.

"D-Company 6-RAR set a standard that goes back to the standard that was set through the First World War, Second World War, where Australian troops had a reputation for being there and doing what had to be done."